1. Field of the Invention
The mechanism for malignancy of mammalian cells has been and continues to be the subject matter of intense investigation. One of the areas which is considered to be promising in the elucidation of the mechanism is the area of oncogenes. While the occurrence of oncogenes was first detected with retroviruses, it now seems reasonably firm that the viral oncogenes have cellular counterparts. The role of the cellular counterparts is not clear. An excellent review of oncogenes, their properties and particularly the src gene may be found in the article by J. Michael Bishop, Scientific American, Mar., 1982:81-93. The article also provides a list of various viral oncogenes, demonstrating that a number of them are involved with phosphorylation.
The src gene is found to be not only active in the malignant cell of chickens, but also in the normal cell. The difference appears to be one of degree, rather than of kind, in that the enzyme expressed by the src gene would appear to be of much higher concentration in the malignant cell as compared to the normal cell.
In order to be able to determine the presence of a tumor cell, it is necessary to be able to distinguish between normal cells and tumor cells. Therefore, the observed property which is to be diagnostic of the tumor cell must be capable of differentiation from a normal cell or from a physiologic fluid of a normal host, where the fluid rather than cells are assayed. Furthermore, the property should not be specific for the individual, but be common to the malignant nature of the cell.
In both diagnosis and treatment, the opportunity for specifically detecting malignant cells is very important. Any technique, in a high percentage of situations where malignancy is suspected, should be able to distinguish malignant cells from normal cells. Furthermore, the diagnostic technique should be useful for a large number of members of the population and not specific for one or a few members of the population.
Because a cancer cell is derived from a normal cell, most of the properties and components of the malignant cell are the same as the normal cell. Furthermore, there is an increasing view that malignancy is a result of a natural process, which in a certain context results in malignancy. In view of the fact that malignancy may be based on normal processes, which at the time in question have an aberrant result, it is not surprising that there has been substantial difficulty in demonstrating observable differences between normal cells and cancer cells over a broad spectrum of allogeneic hosts.
2. Description of the Prior Art
The following papers provide a general description of oncogenes and the role of retroviruses in tumorigenesis: Bishop, Scientific American, supra; Bishop, New England J. of Med. (1980) 303:675-681; Lancet, July 24, 1982, pages 195-196; Cooper, Science (1982) 218:801-806; Varmus, Science (1982) 216:812-820. Papers concerned with specific oncogenes include Becker et al., PNAS USA (1982) 79:3315-3319; Tsuchida et al., Science (1982) 217:937-938 and Dhar et al., ibid., (1982) 217:934-936.